db_block_buffers - can you have too many ?

From: Richard Anstey <ranstey_at_compuserve.com>
Date: Tue, 10 Nov 1998 09:25:51 -0000
Message-ID: <#CmDawID#GA.200@nih2naac.prod2.compuserve.com>

Hello,

I'm a newbie here so please go easy on me..

Running O7.3 on NT Intel multiprocessor.

I had sudden performance problems - typical query response times up by a factor of 10. No change had been made to the box and it's dedicated to Oracle.

The database is quite large - 300 plus tables, and is heavily laden with PLSQL code.

With 256MB RAM on the box, I had increased db_block_buffers well above the sample values shown in init.ora. (but still keeping the SGA size well below total RAM - total SGA size was approx 60MB) Oracle support told me to reduce the db_block_buffers and this did actually solve the problem !?

Can anyone help me to explain this ? Surely the more database blocks you can cached, the better so long as your OS isn't swapping the SGA to disk ? Or am I missing something.

Cheers,

Richard.
ranstey_at_compuserve.com Received on Tue Nov 10 1998 - 03:25:51 CST